The aim of this study is to identify the lysosomal proteinases contained within various oral connective tissus, and to characterize their substrate specificities on natural and artificial substrates. In particular, a new lysosomal enzyme detected in bovine dental pulp will be isolated and characterized and its demonstrated ability to hydrolyze, at acid pH, the prolyl bonds in collagen-related substrates will be fully investigated with reference to its potential contribution to collagen degradation. Fluorogenic substrates will be used in a sensitive fluorometric assay to assay for this enzyme (and other lysosomal enzymes) in human dental pulp, and in normal and inflamed periodontal tissues of human origin.